KYORITSU 4202 - Manual (Page 9)

̶ 7 ̶
5. Measurement principle
This instrument can measure the earth resistance to earth in multi-earthed system.
Let's regard earth resistance under test as Rx, and the other earth resistances as
R
1
, R
2
, …Rn.
Of these earth resistances, R
1
, R
2
, …Rn can be considered that they are
connected in parallel.
And can be regarded as a combined resistance Rs. The Rs can be regarded small
enough against Rx since a combined resistance consists of several resistances.
Following is an equivalent circuit diagram of this circuit.